Periodic mesoporous silica materials were first discovered by Mobil Oil in 1992 for use in petroleum cracking applications. It was envisaged that these larger pore materials would allow for a more effective processing of the heavier hydrocarbon molecules than microporous zeolite catalysts. However, this did not happen because the mesoporous silicas proved to be insufficiently hydrothermally stable, a consequence of their amorphous (e.g. non-crystalline) channel walls. In addition, the acidity of the amorphous walls of Al-doped mesoporous silicas, proved to be much less than that of crystalline Al-modified zeolites. As a consequence, their catalytic properties fell far behind that of zeolites for petroleum cracking. Further, the synthesis of such silica materials was industrially and economically inefficient, and their development and use stalled as a result.
There remains a need for highly acidic, stable, economical, durable periodic mesoporous silica catalysts with crystalline pore walls that exhibit a high chemical and thermal stability, and have low cost of production and use.